Method for coating cylindrical members with a hard material



1934- E. H. TARTRAIS 1,971,433

METHOD FOR COATING CYLINDRICAL MEMBERS WITH A HARD MATERIAL Filed nc. 1a. 1929 s Sheets-Sheet 1 I J0 s I \\a\\ v Aug. 28, 1934. T s 1,971,433

METHOD FOR GOAELING CYLINDRIGAL MEMBERS WITH A HARD MATERIAL Filbd'DGC- 16. 1929 3 Shats-Sheet 2 Aug. 28, 1934. E. H. TARTRAIS METHOD FOR comma CYLINDRICAL MEMBERS, WITH A man MATERIAL Filed Dec. 16. 1929 3 Sheets-Sheet 5 a as Z. yarl'rais '37: MM M Patented Aug. 28, 1934 PATENT; or-Pics METHOD FOR OA'lING CYLINDBIGAL MEMBERS WITH A HARD MATERIAL Eugene Henri Tar-trail, Montmorencp lrance Application December 16, 1929, Serial No. 414,544

In France December 20, 1928 4 Claims. (CL 29-1495) The present invention has for its object, a method for coating male or female cylindrical members with ahard'material. This method is advantageously applicable to mechanical cylindrical members which must resist the wear produced by friction, and such, particularly, as the For the constitution of such members, it is not economical to use a metal or analloy presenting in a uniform manner the hardness required for resisting wear.

The method forming the subject-matter of the invention consists in securing on the parts exposed to wear, sheets of hard materials, and particularly'of nitrided steel, previously shaped for fitting the curvature of the cylindrical surface to becovered, and so prepared that, after being secured in position, they present a smooth surface which simplifies the surface grinding and permits, in some cases, dispensing with finishing work.

The method afiords the beneilt derived from the remarkable hardness of nitrided steels recently discovered, but which are too costly when used for the constitution of homogeneous members.

The accompanying drawings illustrate, by way of example only, various forms of construction of means for carrying out the method forming the subject-matter of the invention.

Figures 1 to 8 refer to the application ofthe .present method to the cylinders of motors or pumps.

Figures 9 and 10 diagrammatically illustrate means for the preparation of the covering sheets madeof hard material.

Figures 11 to 17 illustrate means for coating with a hard metal the inner face of a cylinder.

Figures 18 to 21 illustrate means for coating with a hard metal, male cylindrical members.

Figures 22 and 23 illustrate a structure for securing, by electric welding a hard metal coating or covering within a cylinder.

In the example shown in Figs. 1 and 2, use is made for lining a cylinder, of two half rings made of a. hard material, and such as shown in Fig. 1.

"The edges 1 and i.

cylinder, but long pitch helices-of reverse direction, or again planes approximately similar to such helices By forcing into the cylinder two halfrings thus made, as shown in Fig. 2, and by exert-.

ing a somewhat high pressure on the ends of the rings, according to-the direction of the arrows,--

protecting the are not generatrices of the.

chosen for the helices (or the planes) ensuring irreversibility. The projecting ends 6, 7, 8, 9 are then cut oil and, if need be, the bevel for the entrance of thepiston rings is formed.

The order of the operations is as follows:

The metal or alloy in a soft condition, intended for the manufacture of the rings, is rolled in sheets of the required thickness. It is then callbrated, preferably in the cold state, with a finished rolling mill, the rolls of which are perfectly polished, or at least one of them. The calibrated sheet is thus perfectly polished, at least on one of its faces. This operation is preferably effected on bands or strips of small width for diminishing machine expenses, increasing the accuracy and rendering easier the precautions to be taken for polished surface against any deterioration.

The sheet is then cut out according to the approximate shape of the development of a halfring. This operation can also be eflected before the above mentioned calibrating rolling.

The cut out sheet is then curved, by any method, so as to give the shape shown in Fig. 1. The member is then subjected to the hardening treatment, the necessary precautions being taken during the manipulations. It is preferable that the member which has been subjected to the treatment should have a radius of curvature a little greater than that of the cylinder, sothat it should have a natural tendency to perfectly flt thereon.

'After the treatment, a pickling operation can i be effected by any mechanical or chemical process. I I

.After this pickling or controlling operation, the

member is placed in a jig, such for instance as that shown in Fig. 3. This very rigid jig forces "a grinding wheel such as 3, the edges 4 and 5 of the two companion members are given the exact required shape. The cylinder has, on the other hand, been exactly bored to the required dimension. There remains only to fit the member in the cylinder as above mentioned and as shown in Fig. 2. For facilitating the cutting off of the projecting ends 6, 7, 8, 9 itds convenient that the said projecting ends should not be subjected to the action of the hardening agent.

It is to be noted that in the grinding operation of the edges, it may be advantageous that the edges, once drawn together in the cylinder,

\ freed from traces of oxides.

present the arrangement shown in Fig. 4 so to assure that they are in contact with the cylinder. Of course, the clearance 10 is extremely small, being of the order of one or two hundredths of a millimeter.

, If the cylinder is exactly cylindrical and if the half-rings are suihciently thin, it is obvious that the interior of the assembled ring must have the same qualities, since it is compelled to exactly fit the cylinder and that it has a rigorously constant thickness.

A single slotted ring can also be used (Figs. 7 and 8).

The first operations are the same: calibration and polishing of the alloy in the soft condition. The member is then given the shape shown in Fig. 7. The member is treated and then, as shown in Fig. 8, the edges 13 and 14 ground parallel, owing to tl'iejig 15 (which is larger than the cylinder) and with a grinding wheel 16 having inclined sides. The suitable angle and the width 17 of the opening are then determined by experiments for a given Jig. In sufliciently accurate conditions of execution, the forcible engagement can be effected as if a one-piece ring was under consideration (the edges 13 and 14 meeting each other), but it will be understood that the accuracy is thus much more easily and economically obtained.

The calibration of the sheets of hard metal in the rolling mill is economical. But certain hardening processes necessitate surfaces perfectly For obtaining such surfaces, the surface of the metal sheets to be hardened can be ground or milled. For that purpose, use can be made of the convenient arrangement shown in Fig. 9.

The sheet unwinds from a roll 18 and winds on a roll 19 driven at the required speed by a suitable mechanism. In its movement of translation, the sheet is compelled to fit on a roll 20, opposite which is arranged a grinding wheel 21, or milling cutter having the width of the sheet to be operated upon. For rendering more perfect the application upon the cylinder 20, a device can be provided for stretching the said sheet. The rotation of the roll or reel 1 can for instance be braked by any suitable means.

The grinding or milling can follow or precede the preparation of the sheets in view of protection against hardening (in fact it is advisable in some cases to harden only the inner surface in order to increase the suppleness or flexibility of the finished members). If the grinding (Fig. 10) and the edges '5 are ground according to the required shape. If experience shows that these edges must not be at right angles to the plane of the sheets, the suitable angle will have to be found by experiment.

For placing in position these very flexible flat sheets, it sufllces to clamp them on a mandrel,

by means of'a collar, at the time they are to.

be introduced in the cylinder.

By operating in this way, it is possible to place a great number of sheets in the apparatus where the hardening operation is effected. This advantage is very important in case this operation is of very long duration as in the case for treatment with nitrides.

It is also possible, after hardening of the sheets in a fiat condition, to curve the latter at the time of introducing them in one of the jigs of Figs. 3 and 8, for grinding the edges of the same. When the sheets are made of nitrided steel, the sheets can be hardened flat-wise, and they can be curved in the hot condition, at a temperature of about 500 0., preferably before grinding of the edges.

If a metal or an alloy is operated upon, which to rather small distortions, or if the sheet is sufliciently thin so as to be able to take again the required shape in the grinding jig and upon final engagement into the cylinder, or again if it is curved, in the hot state, after treatment in the special case above indicated, it is possible to harden to the core, or on both faces, which amounts to the same thing. This is useful in case use is made of a metal or alloy which does not lend itself to a treatment allowing to obtain with accuracy a hardened layer of uniform and definite thickness. In this case it is preferable to harden to the core. The member obtained is of course more fragile, but once placed in position and clamped in the cylinder, this does not seem to present any inconvenience. Moreover, it is to be noted that in certain cases it is impossible to only superficially harden the sheets for instance in the hardening by the hardening method of a homogeneous metal or alloy.

The placing in position of the sheets into the cylinder can also be effected as follows:

The sheet adapted to line the cylinder iscut out according to a rectangle A; B, C, D (Fig. 11) having one of its sides A-C equal to the length of the cylinder and the other side A-B being a little greater than the development of the inner circumference of the said cylinder. This sheet is curved, then treated with nitrides, or it is first treatedwith nitrides, according to circumstances. According to the applications, both faces of the sheet can be treated with nitrides, or this sheet can be treated with nitrides to the core, or again only the face which will be subiected to wear, and this by means of any of the protecting methods in general use, for instance by tinning the face which must not be hardened. But, in any case, one of the connecting edges, for instance AC must be hardened, and the metal adjacent to the edge BD (hatched portion) must be left in the soft condition. It is advisable that the edge A-C should be neat and with sharp angles, this being effected, if

need be, by a slight grinding with a grinding 1 stone after treatment.

This being effected, the sheet is placed into the cylinder, as shown in-Flg. 12. The cylinder can be provided with shoulders 23 and 24 for holding the sheet lengthwise. As the sheet is greater than the development of the cylinder, the edges 25 and 26 overlap, 26 being the soft edge.

A tool 29 is then used, as shown in Fig. 13, this tool being provided with a recess 27 and a sharp edge having the shape indicated at 28, and it is caused to forcibly pass from one end of the cylinder to the other. Fig. 14 shows the tool 29 fitted into the cylinder. It is easy to understand that as the tool'advances, the soft edge of the sheet is sheared by the hard edge and the sharp edge 28 150 mm the recess 21. It will be noted, on the other instead of one.

hand, that this method allows of resiliently expanding the cylinder. The sheet is therefore out according to the development of the expanded cylinder. When the tool has passed, the cylinder contracts and the sheet becomes a ring forcibly fitted in position. In proximity to the edge remains a narrow strip of soft metal which has been left as a guard and whichcannot have any influence on the operation.

This method is applicable to sheets of cemented and hardened steel orany other metal or alloy capable of'lending itself, by any treatment, to the production of a hard-edge and a soft edge.

It is possible, in the same manner, to secure in positions sheet divided into several sectors, for instance three sectors, as illustrated in Fig. 15. Each of these three sectors has a hard edge and a soft edge, and the tool has three sharp edges The division is advantageous for large cylinders or in case the members must be curved before treatment, as surved members in one piece occupy considerable space in the furnace.

In any case, if one sheet or several are used, the connections can'be arranged either according to generatrices as already mentioned, or according to long pitch helices. It suilices to give to the tool the corresponding helical movement. The tool can, moreover, simultaneously take this helical movement if the inclination of the helix isin the suitable direction.

Figure 16 illustrates a constructional modification in which both edges and 26 of the sheet are hardenedand sharp. Moreover instead of overlapping, they provide between them a space in which is inserted, always by the same method, a narrow strip 31 of soft metal, sectioned and introduced by the tool 29. At 32 and 33 are indicated the two out edges-of the strip 31. This latter method, which allows also the multiplication of the sectors and the use of helical connections, is applicable to all metals, but it is particularly interesting in that it allows the use of metals on which it is not possible to provide soft portions.

The cylinder can also be expandedby means of a suitable apparatus, the shearing operation being effected by another apparatus.

Figure 17 shows a form Ofapparatus for ex panding the cylinder. This apparatus is constructed accordingto the principle of expansible mandrels. The inner member 34 is of conical shape. It suflices to cause it to enter more or less for expanding the mandrel and, consequently, the cylinder. The sheet is shown in position at 35. The mandrel presses this sheet throughout the length of the cylinder. It then suffices to cause a tool having the'shape shown at 36 to forcibly pass for eifecting the cutting operation. As will be understood, the same is true when several sheets are used, and the edges can also be straight or of helical'shape. The driving of the cone 34 can be effected in any; manner; in the drawing it has beenassumedthat the driving of the cone is effected in the direction of the arrows by means on the shaft, by autogeneous or like welding, and preferably by arc welding.

Thus, for lining with a hardened metal or alloy a crank shaft .iournal 3'1 (Fig. 18), the latter is prepared, for receiving a ring in two parts (Fig. 19) or half-shells 38 and 39, made of nitrided steel for instance.

, Holes such as 40 can serve for the passage of lubricating oil.

Figure 20 shows the whole structure assembled for welding. The half-shells, 38 and 39 are pressed on the journal 37 by the jaws 41 and 42 of a hydraulic press, for instance, or in any other manner, After that, two operators each carrying an electrode, have simply to effect, together. an arc welding operation in the housings or bevels 43 and 44. The half-shells are thus welded together and on the journal and, owing to the resilient compression exerted by the press on the latter during the welding operation, the ring thus constituted is clampedon the Journal as in forcible engagement. This is advantageous for avoiding loosening in case of a slight difference of temperature, in operation.

In order that the resilient compression of the shaft should effectively take place, (and not a simple oval shaping) the jaws 41 and 42 made of high resistance metal and of large dimensions may have internallya radius of curvature smaller than that of the member to be clamped. The compression is, moreover, promoted in same case by the inner recess of the shaft.

All the rings being assured in position, there remain only to remove theexcess of metal, either with a file, milling cutter or grinding wheel, or by cylindrical connection, or again by forming a. flat portion. The joints must, of course be arranged in the regions subjected to smallest strains during the operation.

If the shaft has been machined with accuracy,

and if the half-shells are made of calibrated and polished sheet metal, the grinding of the surfaces after the rings have been secured in position, may be dispensed with.

If the thickness of the sheet metal is very small relatively to the diameter of the shaft, the rings canbe made of a single rolled up sheet, as shown in Fig. 21. This sheetis resilently opened. itspassing it over the shaft. A soft portion can provided at 45, so that the member can be opened by folding it at this place and closed again in the same way. Two or more soft zones can 11.51, be provided.

Female cylindrical members can also be lined in this manner, for instance cylinders of motors or pumps. In this case, the ring is preferabiy made of a single rolled up sheet. It is placed in the cylinder and applied by an expanding apparatus or mechanism. a

This expanding apparatus can act throughout the length of the cylinder at the same time, c it can be moved forward or backward by hand or automatically, in proportion as the welding operation proceeds. The whole length of til welding can be effected from a single end, or om half of the welding from each end.

A single example is described and illustrated in Figs. 22 and 23. It. refers to a cylinder cast in one piece with its cylinder head.

The cylinder 46 is secured on a jig 4'7 after having successively introduced therein a tool 48 and the ring 49. This tool 48 is provided with two recesses: a small recess 50 wherein will enter the excess of solder, and a larger recess 51 for facilitating the welding operation. It can also carry a mirror 52 for allowing the operation to be followed. The tool 48 is caused to move forward in the direction of the arrow, by any means, so as to engage it into the ring. The latter abuts at 53 on the jig and is placed exactly in' the position it must occupy. The operator will begin to effect the welding operation. For that purpose, he can secure his electrode on a special tool for giving it a favourable inclination, if this is necessary, During the time the operator effects the welding operation, the tool 48 moves forward, its movement being controlled by hand or automatically. In any case, the operator must always weld near the tool 48, that is to say in the expanded portion. The cylinder and tool can be cooled by a circulation of water. It will also be noted that the electrode can be secured on the tool, so as to be exactly in a suitable position relatively to the joint of the ring, and that the constant spacing apart can be obtained by a regulator. The skill of the operator is of no consequence, as the entire operation is automatic.

When the tool arrives .at the end of its work, it can operate a switch. In this way, one operator can, without danger, control several apparatuses.

Moreover, if the cylinder is cast in groups of 4, 6 or 8 cylinders, all the weldings of one and the same group are effected at the same time while the operator equips another group. Finally the operation thus taking place in a perfectly regular manner, the welding can be made very small, thus reducing to the minimum the expense of current and the time required for the operation.

The welding being finished, there remains only to remove the excess of metal by any means, the

- simplest of which is the use of a tool of the type called out mandrel.

If calibrated and polished sheet metal is used, the grinding operation can be avoided. The cylinder can, however, be finished by a polishing operation. The bevel at the base of the cylinder, for allowing the piston rings to be inserted, can be formed before or after the ring has been secured in position.

The soft zone (solder) or softened zone (proximity of the solder) is, if the operation has been well done, of very small width and cannot have any influence on the operation. It will be noted, moreover, that, in certain cases, particularly if use is made of nitrided steel, the softened zone does not practically exist.

Finally it must be noted that the multiple and automatic welding method is applicable, not only to cylinders, but also to shafts. For this application, it is simply necessary to use a press having the required number of jaws. The electrode supports are secured on one and the same jig which automatically moves parallel to the shaft. This displacement controls the interruption or successive interruptions of current according to the lengths of corresponding journals.

What I claim as my invention and desire to secure by Letters Patent, is:-

1. A method of applying a sheet of hard metal to cylindrical members, consisting in hardening the sheet with the exception of one edge thereof, applying the sheet to the cylindrical member with the unhardened edge overlying one of the hardened edges, and cutting away the unhardened overlying edge.

2. A method of applying a sheet of hard metal to cylindrical members, consisting in hardening the sheet with the exception of one edge thereof, applying the sheet to the cylindrical memher with the unhardened edge overlying one of the hardened edges, and cutting away the unhardened overlying edge by the adjacent hardened edge.

3. A method of applying a sheet of hard metal to cylindrical members, consisting in applying the sheet to the cylindrical member with the edges overlapped, expanding the sheet and the cylindrical member, cutting off the excess material of the sheet and allowing the cylindrical member and sheet to resume normal shape.

4. A method of lining bearings, engine cylinders and like machine parts, consisting in boring the machine part to exactly the desired shape, forcibly fitting a lining sheet of precise thickness in the machine part, said lining sheet being thin enough whereby after having been forcibly applied it fits tightly in all parts against the wall of the machine part.

, EUGENE HENRI TARTRAIS. 

